sony vgn t91ps battery wont charge

sony vgn t91ps battery wont charge ? First, some background information, when a Sony laptop does not recognize the ac adapter, then it will not allow the adapter to charge the battery, thus forming the issue you have right now. So do not buy a universal charger as Sony will not recognize that either.

Now, to "try" to fix the issue, follow the steps posted by Sony,
If that works, great, if it doesn't then most likely you will have to buy another charger.